RC788-61112 hydraulic pump for Kubota U35-4 KX033-4 mini excavator
If you decide to buy equipment at a low price, make sure that you communicate with the real seller. Find out as much information about the owner of the equipment as possible. One way of cheating is to represent yourself as a real company. In case of suspicion, inform us about this for additional control, through the feedback form.
Before you decide to make a purchase, carefully review several sales offers to understand the average cost of your chosen equipment. If the price of the offer you like is much lower than similar offers, think about it. A significant price difference may indicate hidden defects or an attempt by the seller to commit fraudulent acts.
Do not buy products which price is too different from the average price for similar equipment.
Do not give consent to dubious pledges and prepaid goods. In case of doubt, do not be afraid to clarify details, ask for additional photographs and documents for equipment, check the authenticity of documents, ask questions.
The most common type of fraud. Unfair sellers may request a certain amount of advance payment to “book” your right to purchase equipment. Thus, fraudsters can collect a large amount and disappear, no longer get in touch.
- Transfer of prepayment to the card
- Do not make an advance payment without paperwork confirming the process of transferring money, if during the communication the seller is in doubt.
- Transfer to the “Trustee” account
- Such a request should be alarming, most likely you are communicating with a fraudster.
- Transfer to a company account with a similar name
- Be careful, fraudsters may disguise themselves as well-known companies, making minor changes to the name. Do not transfer funds if the company name is in doubt.
- Substitution of own details in the invoice of a real company
- Before making a transfer, make sure that the specified details are correct, and whether they relate to the specified company.
Seller's contacts
+86 199 246...
+86 199 2461 6345
China
China
China
China
China
China
China
China
China
China
China
China
China
China
China
Romania, Targu Mrues
Lithuania, Telšiai
Lithuania, Telšiai
Romania
Mexico, Chihuahua
1. Part Identification & Supercession
This pump has undergone several engineering updates. The latest part numbers reflect improvements in seal durability and volumetric efficiency.
Kubota Genuine Part Numbers: RC788-61112, RC788-61113, RC788-61122, RC788-61123, RC788-61124 (Current Standard)
OEM Model: Nachi PVD-0B-28P-6G3-5243A (or similar suffixes)
Machine Models: Kubota U35-4, KX033-4, U30-4
2. Core Performance Data
Item,Specification,Unit
Pump Type,Variable Displacement Axial Piston,-
Number of Main Outlets,2 (P1 & P2),-
Main Pump Displacement,28.0×2,cm3/rev
Gear Pump (Pilot) Displacement,10.8,cm3/rev
Rated Operating Pressure,23.5,MPa (3408 psi)
Maximum Surge Pressure,27.0,MPa (3916 psi)
Rated Speed,2200−2400,rpm
Max. Theoretical Flow,67.2×2+25.9,L/min (@ 2400 rpm)
3. Critical Internal Components (Hard Data)
For overhaul and repair, the following internal specifications are used to determine wear limits:
Cylinder Block & Pistons:
Piston Quantity: 9 Pistons per group.
Piston Diameter: Standardized for the 28P series to ensure high-pressure sealing.
Clearance Limit: Piston-to-cylinder bore clearance exceeding $0.05$ mm usually results in significant volumetric loss.
Valve Plate:
Surface Flatness: Must be within $0.002$ mm.
Configuration: M-type or standard porting designed for "Load Sensing" (LS) signal stability.
Drive Shaft:
Spline Count: 13 Teeth or 15 Teeth (dependent on the engine flywheel coupling).
Bearing Type: High-load needle roller bearings for the swashplate support and tapered roller bearings for the main shaft.
4. Hydraulic System Pressure SettingsAfter installing a new RC788-61124 pump, the machine must be calibrated to the following factory pressures:Main Relief Pressure: $23.5 \pm 0.5$ MPa (Measured at the control valve block).Pilot Control Pressure: $3.7$ MPa ($536$ psi). If this pressure is low, the joysticks will feel "heavy" and the machine will lack speed.Unloading Pressure: $3.0 - 4.2$ MPa. This is the pressure when the controls are in neutral.LS (Load Sensing) Differential Pressure: Usually set to $1.5 - 2.0$ MPa above tank pressure to ensure immediate pump response.
5. Installation & Commissioning Protocol
To avoid "infant mortality" of the new pump, follow these precise steps:
Case Drain Priming (CRITICAL): Before starting the engine, you must fill the pump casing with clean hydraulic oil through the highest drain port. Running the pump dry for even 30 seconds will score the piston shoes.
System Decontamination: If the previous pump suffered a "catastrophic failure" (metal shards in the oil), you must flush the entire hydraulic circuit and clean the control valve spools.
Filtration: Replace the Return Filter and the Suction Strainer. Check the magnetic plug in the hydraulic tank for debris.
Air Bleeding: Start the engine and run at low idle for 5 minutes without operating the cylinders. Gradually move the cylinders to full stroke to purge air from the lines.